The present invention relates to pen plotters and, more particularly, to a mechanism for cleaning the tips of pens employed therein during a pickup operation to or from a turret containing multiple pens.
In a pen plotter, an ink-containing pen is carried by a pen carriage over the surface of a plotting media. The pen has a plotting tip communicating with the ink which forms the plot-lines on the media when the tip is lowered by the pen carriage into contact with the media. Quite often, the plotter has a storage area outside of the plotting area where pens having different sized tips and/or colors are stored. During the plotting process, the pen carriage can go off-plot to the storage area and exchange pens as required for drawing lines of different widths and/or colors. All this, of course, is usually done automatically. Thus, once the pens are loaded by an operator into holding and exchanging apparatus in the storage area, the operator has no control over the condition of the pen tips.
Most plotting areas are not an environmentally clean environment like the so-called clean rooms where microelectronic parts are assembled. Thus, air-borne particles such as dust, lint, fuzz, hair, etc. can get onto the plotting media and from there to the pen tip to interfere with the accurate drawing of lines of the intended width. A small hair, for example, can trail behind the pen tip conducting a portion of the ink away from the tip and onto the surface of the plotting media creating a pattern of fine lines which ruin the plot for most purposes.
While most plotters having off-plot pen-holding devices include pen-capping members for "capping" the pen tips while in storage, such pen-capping members serve only to keep the pen tips from drying out due to evaporation in air and do nothing to clean the tips and remove any foreign matter therefrom.
Wherefore, it is the object of this invention to provide pen tip cleaning apparatus for a multi-pen plotter which automatically and thoroughly cleans the tips of the pens each time that they are picked up or replaced by the pen carriage for use.
Other objects and benefits of the invention will become apparent from the detailed description which follows hereinafter when taken in conjunction with the drawing figures which accompany it.